How does the relationship between Mariam and Laila develop through part 3 thousand splendid suns?

In "A Thousand Splendid Suns," the relationship between Mariam and Laila evolves from initial mistrust and resentment to a deep bond of friendship and sisterhood. They find common ground in their shared struggles and unite against their abusive husband. Over time, they become each other's source of strength and support in the face of adversity.